S40 P0030, P0037, P0136 DTCs

DanielV · Post by **DanielV** » 07 Nov 2018, 05:23

Hey guys!

So my 2008 S40 (125.000 Km/77.000 Miles) is throwing P0030, P0037 and P0136 codes.

After some research, I replaced both O2 sensors, but nothing changed at all.
Codes erased, 3 cycles and it comes back.

I measured the wires of the O2s, and turned to be good, even with the old ones.
Then I measured the O2 sensors connector signal wire goes to the ECM and everything's fine. Fuses also work properly.

The diagnostic tool tells both sensor are at 0.42 V, but stuck on that voltage.

The local Volvo dealer told me, my catalytic converter needs to be replaced.
Another mechanic who only repairs Volvos assumed, my ECM needs to be replaced.

The car runs fine, like before the codes have shown up.

Has anyone else had this problem before?
Should I go and replace the cat or the ECM?
Or maybe should I check something else before replacing?

Thank you!

Post by **RickHaleParker** » 09 Nov 2018, 13:36

Which engine and transmission?

DanielV · Post by **DanielV** » 09 Nov 2018, 23:55

It's a manual 5 speed, 1.6 (B4164S3).

Post by **RickHaleParker** » 10 Nov 2018, 09:36

EUR/INT 2008 S40 Engine: B4164S3 Transmission IB5.

I'm thinking you got a problem in your O2 power supply. In the engine compartment, Relay 14 and Fuse 32.

The O2 power supply is the Green-Red on one of the O2 sensors and Green-Yellow on the other (Electrical terminal #2 on the O2 sensor).

DanielV · Post by **DanielV** » 10 Nov 2018, 10:21

Thank you!
I'll check them tomorrow and let you know!

DanielV · Post by **DanielV** » 11 Nov 2018, 05:47

So I checked all you mentioned above, but no luck.
There are continuity in the wires. Relay and fuse work fine as well.
Thinking of when my CEL first shown up. It was few days after my instrument panel's fuse blown (F 46) (that was my bad, changing not the correct way the trunk light).
Just wanted to let you know, altough I think that's not supposed to cause problems like mine.

Post by **RickHaleParker** » 11 Nov 2018, 11:22

Do you have voltage to the O2 sensors?

DanielV · Post by **DanielV** » 11 Nov 2018, 13:11

Yes. Both sensors show 0.42 V, but steady.
I read that the sensor before the cat, should be changing voltage. But it doesn't, even while revving.
Maybe from 0.42 to 0.43 V.

Post by **RickHaleParker** » 11 Nov 2018, 16:44

0.42V on Electrical terminal #2 of the O2 sensors? ... something is not right in your supply voltage. I did say voltage to not output voltage.

DanielV · Post by **DanielV** » 11 Nov 2018, 23:51

Sorry, I think that will be the problem, because I'm not seeing any voltage to terminal #2.
I attached some pics in case you want to see its condition.
Should I replace something?

I really appreciate your help!